Importing a Secret Recovery Phrase into MetaMask will REMOVE all existing user data from MetaMask. In other words, if you are using one SRP in MetaMask, and you import another one, all data relating to the first SRP will no longer be accessible through the application.
Before proceeding, make sure you have your Secret Recovery Phrase and any private keys (from hardware wallets or imported accounts) backed up, and your accounts will be safe.
If you have unintentionally done this, and need to recover an SRP that you previously used in MetaMask, you may still be able to. See this article for guidance.
